1. Field of the Invention
The present invention relates to novel pyrimidine derivatives and optical isomers thereof as well as to a herbicide containing one or more of the said derivatives as an active ingredient.
2. Description of the Prior Art
Hitherto, it is generally said that the economic cost in the use of a herbicide depends upon the necessary amount of the active ingredient in the herbicide to be applied to a unit area, and therefore, development of a novel herbicide which displays a sufficient herbicidal effect even in a small amount to be used is desired.
It is known that some conventional herbicides would often have a bad influence on crops when applied thereto. Accordingly, studies have been effected for a long period of time for the purpose of obtaining compounds which may display a high herbicidal effect even in a small amount to be used and which may also display a high selectivity between the crops to be protected and the harmful weeds to be destroyed.
For instance, Japanese Patent Laid open No. 54-55729 illustrates a herbicide containing a pyrimidine nucleus-having compound as an active ingredient.